1. Field
Apparatuses and methods consistent with exemplary embodiments relate to a charging and discharging system for a solar light power generator in a real-time pricing environment used by a smart grid, a duplex converter of the charging and discharging system, and a charging and discharging method for a solar light power generator. More particularly, apparatuses and methods consistent with exemplary embodiments relate to a charging and discharging system in which electricity is charged into a battery of the charging and discharging system from a solar light power generator, the charged electricity is sold to an electric grid (e.g., a power network, a smart grid or a power grid), and the electricity of the electric grid is charged into the battery when the electricity price of the real-time price is determined to be low regardless of solar light power generation, to a duplex converter of the charging and discharging system and to a charging and discharging method for a solar light power generator.
2. Description of the Related Art
With the exceedingly rapid advancements in modern society, energy consumption is geometrically increasing, and causing many environmental problems including the generation of carbon dioxide (CO2). Accordingly, in recent industrial developments, overcoming the environmental problems and efficient use of electric energy are considered very important.
Furthermore, as a result of the development of renewable energy, solar light power generators have remarkably spread. Typically, a solar light power generator produces electric energy from a solar light module so that such electric energy is used as energy, and is connected to an electric grid to sell electricity.
However, in order to increase the effect relative to the investment based on the real-time pricing used by a smart grid, the usability of a battery in which a costly investment is made should be increased, in addition to using a typical method. The battery is bound to a mechanical device of the solar light power generator, and the smart grid is a next-generation intelligent network in which information technology (IT) is added to a related art power network so that a power supplier and a consumer interchange real-time information with each other, thereby optimizing energy efficiency.
In order to increase the usability of the battery, the energy stored as a result of power generation using solar light energy is sold at an optimal price depending on the real-time pricing of the electric grid. In the case where the energy price of the electric grid is low (e.g., at nighttime), there may be a need to store energy in the battery using the energy of the electric grid to sell it at an optimal price.
A system that satisfies such a need may include all four devices of a DC to DC converter (i.e., a battery) for charging solar light energy, a maximum power point tracking or maximum power point transient (MPPT) system for maximally utilizing solar light energy production, a grid-connected inverter for selling electricity charged into the battery to an electric grid, and a rectifier for charging the battery with electricity of the electric grid when the electricity price of the electric grid is low.
When all of four devices are constructed together, cost, efficiency, or installation space problems may occur and there may be a problem related to miniaturization for home use. Hence, there is urgently needed a technique that achieves a single power conversion system having the above four operations.